Important Short Questions and Answers: Mechanical Energy Based Processes

1.  State the working principle of Abrasive Jet Machining?

In abrasive jet machining process, a high speed stream of abrasive particles mixed with high pressure air or gas are injected through a nozzle on the work piece to be machined.

2.     List any four advantages of AJM process?

a.     This process is suitable for cutting all materials. Even diamond can be cut by using diamond as abrasive.

b.     Initial investment is low.

c.      It can be used to cut intricate hole shapes In hard and brittle materials.

d.     There is no heat generation during this process. So, thermal damage to the workpiece is avoided.

3.     What are the applications of AJM process?

This process is widely used for

a.     Machining of hard and brittle materials like quartz, ceramics, glass, sapphire, etc.,

b.     Fine drilling and micro welding.

c.      Cleaning and polishing of plastics, nylon and Teflon components.

d.     Machining of semiconductors.

4.     What are the factors that affect the material removal rate in AJM process? The following factors will affect the material removal rate in AJM process.

a.     Mass flow rate

b.     Abrasive grain size

c.      Gas pressure

d.     Velocity of abrasive particles

e.      Mixing ratio

f.       Nozzle tip clearance.

5.     What is water jet machining process?

In water jet machining process, high pressure and high velocity stream of water is

used to cut the relatively softer and non- metallic materials like paper board, wood, plastics, rubber, fibre glass, leather etc.,

6.  State the working principles of HJM process?

In hydrodynamic jet machining process, abrasive particles are added to the high velocity stream of water jet and the material is removed from the workpiece due to the combined effect of abrasion and water impact.

7.     List the unique benefits offered by WJM process?

a.     In WJM process, water is used as energy transfer medium. It is cheap, non-toxic and easy to dispose.

b.     Low operating cost.

c.      The work area remains clean and dust free.

d.     Low maintenance cost.

8.     Differentiate abrasive jet machining process and sand blasting process?

Abrasive Jet Machining (AJM) is basically meant for metal removal with the use of small abrasive particles, whereas the san blasting process is a surface cleaning process which does not involve any metal cutting.

9.  State the working principle of ultrasonic machining process?

In ultrasonic machining process, a slurry of small abrasive particles are forced against the workpiece by means of a vibrating tool and it causes the removal of metal from the workpiece in the form of extremely small chips.

10. What are the types of transducers used in ultrasonic machining processes?

There are two types of transducers used in ultrasonic machining processes for the production of ultrasonic waver. They are

a.     Magnetostriction transducer

b.     Piezoelectric transducer.

11. What is magnetostriction effect?

When a rod of ferromagnetic material such as iron or nickel is kept in a magnetic field to its length, the rod suffers a change in its length. This phenomenon is known as magnetostrictition effect.

12. What is piezoelectric effect?

When mechanical force is applied to one pair r of opposite faces of certain crystals like quartz, tourmaline, etc., equal and opposite electrical charges appear across its other faces.

13. What is feed mechanism and state its types?

Feed system is used to apply the static load between the tool and workpiece during ultrasonic machining operation. There are three types of feed mechanism. They are:

a.     Gravity feed mechanism

b.     Spring loaded feed mechanism

c.      Pneumatic or hydraulic feed mechanism.

14. State tool wear ratio?

Wear ratio is defined as the ratio of volume of material removed from the work to volume of material eroded from tool.

Wear ratio = Volume of material removed from work/ Volume of material eroded from tool.

15.                  Write the typical applications of ultrasonic machining?

a.     Holes as small as 0.1 mm can be drilled.

b.     Precise and intricate shaped articles can be machined.

c.      It is used for making tungsten carbide and diamond wire drawing dies for forging and extrusion processes.

d.     It has been efficiently applied to machine glass, ceramics, tungsten, precision mineral stones, etc.,